Methods and devices for detection of context when addressing a medical condition of a patient

ABSTRACT

Methods and devices detect context related to a patient when monitoring a physiological condition of the patient and/or when applying one or more modes of therapy. The context may be a patient context such as posture or an environmental context such as ambient conditions. The context may be used in various ways in relation to the physiological measurement, such as to control when the physiological measurements are made, to appropriately flag physiological measurements, to be recorded in association with the physiological measurements, and/or to correct the physiological measurements based on a reference context. A device such as a beacon transmitter is used in detecting the context and a measurement device such as an implantable cardiovascular device is used to capture the physiological measurements.

RELATED APPLICATIONS

This application is a Divisional of U.S. application Ser. No.12/171,210, filed Jul. 10, 2008, entitled “Methods and Device forDetection of Context when Addressing a Medical Condition of a Patient,”now issued as U.S. Pat. No. 7,986,998, which is a Divisional of U.S.application Ser. No. 10/269,611, filed Oct. 11, 2002, entitled “Methodsand Device for Detection of Context when Addressing a Medical Conditionof a Patient,” now issued as U.S. Pat. No. 7,400,928, which areincorporated herein by reference.

TECHNICAL FIELD

The present invention relates to monitoring physiological conditionsand/or treating a medical condition of a patient. More specifically, thepresent invention relates to detecting a context that is related to thephysiological condition and/or treatment of the patient.

BACKGROUND

Physiological conditions of a patient may be monitored either duringvisits to a physician or through frequent self-examinations by thepatient. Although the health of the patient may be determinable fromthese monitoring sessions, certain health issues may not be readilyapparent from such periodic monitoring. Additionally, periodicmonitoring through self-examination and visits to a physician can be aninconvenience to the patient.

Medical devices that are coupled to the patient either periodically orconstantly, as in the case of an implant, address many of these issues.The patient is not encumbered by the manual self-examination and is notrequired to make frequent visits to a physician. Instead, the medicaldevice automatically makes measurements of a physiological condition ofthe patient, such as pulse or respiration rate, and stores theinformation for later retrieval or streams the data to another device orcommunication network. Thus, the physiological condition of the patientcan be automatically monitored at anytime during which the medicaldevice is coupled to the patient, regardless of context.

However, context may temporarily affect the physiological condition ofthe patient being monitored. Context can be divided into both a patientcontext and an environmental context. The patient context is abody-related factor, such as the posture, activity level, ormental/emotional state of the patient, and the patient context can causethe physiological condition of the patient to vary to a substantialdegree. The environmental context is an external factor such as theambient temperature or sound level and can also cause the physiologicalcondition to vary.

The context is typically unknown when the medical device is making thephysiological measurements, and therefore any deviations from normalvalues for a physiological condition may be the result of context ratherthan a health condition of the patient. Therefore, the physiologicalmeasurements being made regardless of context cannot be relied upon witha high degree of certainty when assessing the health of the patientsince the unknown context may skew the measurements.

Additionally, the context may be relevant to the type of therapy that isbeing provided to a patient. For example, for certain contexts thepatient may be better served by a particular mode of therapy from amedical device, such as immediate defibrillator shocks while drivingupon detection of fibrillation. For other contexts, the patient may bebetter served by a different mode of therapy from the medical device,such as taking more time to more accurately determine the patient'scondition before administering defibrillator shocks. However, becausethe context is typically unknown, the medical device administers thedefibrillator shocks without regard for the context surrounding thepatient at any given time.

SUMMARY

Embodiments of the present invention address these problems and othersby detecting the context when monitoring the physiological condition ofthe patient and/or when providing therapy to the patient. Thus, aparticular context may be used in various ways in relation to themeasurements of physiological condition and/or in relation to the typeof therapy to be provided at any given time. For example, context may beused to control when the measurement of physiological conditions occurs,may be used to flag the measurements that occur, may be recorded inassociation with the physiological condition, or may be used to correctthe measurements of the physiological condition according to a referencecontext. Similarly, the context may be used to determine when to providea particular mode of therapy to a patient to address a medicalcondition.

One embodiment of the present invention involves utilizing a device todetect whether at least one contextual condition associated with thepatient exists. When the existence of the at least one contextualcondition is detected, the at least one physiological condition of thepatient is automatically measured using a measurement device coupled tothe patient.

Another embodiment involves measuring at least one physiologicalcondition of the patient with a measurement device. While measuring theat least one physiological condition, an external device is utilized todetect whether at least one contextual condition associated with thepatient exists. The measurements resulting from the measuring done whilethe at least one contextual condition continues to exist are flagged.

Another embodiment involves measuring at least one physiologicalcondition of the patient using a measurement device. An external deviceis utilized to measure at least one condition defining a patientcontext. The measurements of the at least one physiological conditionare correlated with the measurements of the at least one conditiondefining the patient context.

Another embodiment provides therapy to a patient. This embodimentinvolves utilizing a device to detect whether the patient is within apredefined proximity. When the patient is within the predefinedproximity, a first mode of therapy is provided to the patient with amedical device.

Another embodiment also involves providing therapy to a patient. Thisembodiment involves utilizing a device to detect whether at least onecontextual condition associated with the patient exists. A first mode oftherapy is provided to the patient from a medical device while the atleast one contextual condition continues to exists.

DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a patient to be monitored and examples of the variouspatient contexts that may exist during physiological measurements and/ortherapy delivery.

FIG. 2 shows an example of a patient being monitored and/or treated witha mode of therapy while a patient context is being detected throughproximity sensing.

FIG. 3 is a block diagram of the major components of embodiments ofdevices of a first illustrative system for detecting context whenmeasuring physiological conditions of the patient or providing a mode oftherapy to the patient.

FIG. 4 shows another example of a patient being monitored or provided amode of therapy while a patient context is being detected throughproximity sensing.

FIG. 5 shows an embodiment of the logical operations of an illustrativesystem for detecting patient context to start and stop the measurementsof physiological conditions and/or to switch between first and secondmodes of therapy.

FIG. 6 shows another embodiment of the logical operations of anillustrative system for detecting patient context to flag themeasurements of physiological conditions and/or to switch between firstand second modes of therapy.

FIG. 7 is a block diagram of the major components of embodiments ofdevices of a second illustrative system for detecting context whenmeasuring physiological conditions of the patient and/or providing amode of therapy through proximity sensing.

FIG. 8 is a block diagram of the major components of embodiments ofdevices of a third illustrative system for detecting context whenmeasuring physiological conditions of the patient and/or providing amode of therapy through proximity sensing.

FIG. 9 shows an additional embodiment of the logical operations of anillustrative system for detecting patient context when measuringphysiological conditions and/or when providing a first or second mode oftherapy through monitoring ingress and egress.

DETAILED DESCRIPTION

Embodiments of the present invention detect the context that exists whenmeasurements of physiological conditions of the patient are measuredand/or when one or modes of therapy are applied to the patient. Thecontext may be correlated with the physiological measurements in variousways so that the context from one set of measurements to the next doesnot influence the physiological measurements and their value inassessing the health of the patient and the control of therapy to thepatient.

As shown in FIG. 1, a patient 100 may be monitored and/or treatedperiodically or continuously by a measurement device 102 that is coupledto the body of the patient 100. The patient 100 may experience variouscontextual conditions including various patient contexts andenvironmental contexts. As shown in FIG. 1, examples of patient contextsinclude a sleeping or lying down context 104, a running context 106, anda driving context 108. Each of these different patient contexts mayaffect the physiological condition being monitored in various ways. Forexample, pulse rate may be monitored and may decrease relative to abaseline level in sleeping context 104 but be increased relative to thebaseline level in the running context 106 or driving context 108.Likewise, the patient context at any given time may be relevant to themode of therapy to be applied to the patient.

To increase the value of the physiological measurements taken for thepatient 100, it is desirable to correlate the context with thephysiological measurements. The correlation may be brought about bydetecting context and only taking measurements of the physiologicalcondition when the context is as expected. Doing so provides arepeatable baseline for the measurements so that one set of measurementsmay be compared to the next or to known normal values to determinetrends or deviations from normal values that indicate a health problem.Correlation may be brought about by detecting the context and flaggingthe measurements that are taken so that those taken during a particularcontext are flagged and may be used as the repeatable baseline, orconversely, not considered. Correlation may also be brought about bylogging the context with the physiological measurements so that contextmay be considered upon reviewing the measurements. Additionally, contextmay be used to determine a correction for the measurements to normalizethe measurements according to a baseline context.

To increase the effectiveness, safety, or other concern for therapybeing provided to the patient 100, it is also desirable to determine thecontext when deciding what mode of therapy should be applied. Onepatient context may dictate that a particular mode of therapy not beused. For example, a mode of therapy may provide defibrillator shocksimmediately upon detection of an abnormal rhythm, but such a form oftherapy may be unsafe and/or unnecessarily uncomfortable for the patientbecause initial signs of fibrillation may not always call fordefibrillator shocks. Therefore, when time is available, a proper modeof therapy may be to analyze over a relatively longer period of time thepotential fibrillation condition of the patient to make a more accuratedecision about the need for defibrillation. However, under othercontexts such as while the patient is driving a car, it may be moreappropriate to immediately administer the defibrillator shock uponinitial detection of fibrillation to prevent the patient from losingconsciousness. Thus, detecting the context allows a most appropriatemode of therapy to be chosen.

FIG. 2 shows one example of context detection. In this example, patientcontext is detected by proximity sensing. The patient 100 is lying downin bed and this position likely affects various physiological conditionsof the patient that may be measured and may also dictate the mode oftherapy to be provided. A measurement device 102 such as an implantablemedical device is coupled to the patient 100. An external device 202,such as a beacon transmitter is positioned nearby the bed of thepatient. When the patient lies down in bed, the measurement device 102becomes within transmission range of the beacon transmitter 202. Uponreceiving the transmitted signal 204 defining the transmission range,the measurement device behaves so as to allow correlation of thephysiological measurements with the context of lying down. Upon themeasurement device 102 moving out of range wherein the signal 206 is tooweak, the measurement device 102 may behave differently because thedetection of context has indicated a change. The patient can no longerbe lying down in bed once the signal 204 is out of range. Likewise, onemode of therapy may be provided to the patient 100 when in the beaconsignal 204 is received while another mode is provided otherwise.

As an example of how the measurement device 102 may respond to thedetection of context, the measurement device 102 may begin takingmeasurements of a physiological condition such as pulse rate once themeasurement device 102 is in range of the transmitter 202.Alternatively, the measurement device 102 can flag data as beingrecorded during an appropriate patient context so that the data isacceptable. As another alternative, the measurement device 102 can logthe particular patient context being experienced with the measurementdata, such as where the transmission signal 204 provides an ID of thetransmitter 202 to the measurement device 102. In this scenario,multiple transmitters may be used to provide information regardingmultiple patient contexts such as one for sleeping and one for driving.As another alternative, the measurement device 102 may employ algorithmsto normalize or correct the measurements to correspond to those takenduring a baseline context different than the present patient context.This may be done by applying correction factors associated with thepresent patient context (e.g., multiply pulse rate by a factor of 1.3when pulse rate is recorded while the patient is lying down toapproximate upright and awake pulse rate).

FIG. 3 shows the major components of a system for detecting context whenmaking measurements of physiological conditions and/or when applying oneor more modes of therapy to a patient. The system includes the externaldevice 202 and the measurement device 102. The external device 202includes a transmitter 302 that produces the signals received by themeasurement device 102 when in range. The transmitter 302 typicallyoutputs radio frequency electromagnetic signals that have a range thatmay be controlled based upon the power output of the transmitter 302,which may be user adjustable to adapt to various situations. Theexternal device 202 can include various other features in addition tothe transmitter 302 if additional functionality is desired.

For example, the external device may include a control circuit 314 thatis operatively coupled to the transmitter 302 to turn the transmitter onand off according to one or more parameters. For example, it may bedesirable to transmit the signal to the measurement device 102 toinitiate measurements or a certain mode of therapy only during certaintimes of day and the controller 314 turns the transmitter 302 on and offaccording to the time of day. Thus, the time of day controls themeasurements of physiological condition or the mode of therapy by themeasurement device 102 in addition to the patient context. Environmentalsensors 316 that are operatively coupled to the controller 314 may alsobe included so that the controller 314 turns the transmitter 302 on andoff according to ambient conditions such as temperature or humidity thatdefine an environmental context. Thus, the environmental context cancontrol the measurements of physiological condition and/or the mode oftherapy by the measurement device 102 in addition to the patientcontext.

The external device 202 may also include a receiver 312 operativelycoupled to the controller 314. The receiver 312 can be used to receiveinformation from the measurement device 102 for embodiments of themeasurement device 102 that include a transmitter. As one example, themeasurement device 102 may transmit the measurements of thephysiological condition either in real time or after some period ofstorage to the receiver 312. The receiver 312 then passes the data tothe controller 314 that may also act as a data logger to store the datain memory or pass it through a network connection. The data controller314 may add the environmental context taken from the environmentalsensor 316 to storage in association with the measurement data, and mayadd the patient context established by the external device 202, such asthe sleeping context, to storage as well.

The measurement device 102 includes a detector such as receiver 304 thatis coupled to a controller 306 and that signals to the controller 306when the signal from the external device 202 is in range. Upon receivingthe signal from the receiver 304, the controller 306 begins the activitythat permits correlation of the patient context to the measurements ofthe physiological condition, such as beginning taking the measurementsor flagging the measurements that are taken from that point forward.Additionally, or alternatively, the controller 306 may choose the modeof therapy to apply upon receiving the signal from receiver 304. Asensor 308 is operatively coupled to the controller 306 so that themeasurements acquired by the sensor 308 may be passed to the controllerto be stored in memory or transmitted to the external device 202 if themeasurement device 102 is equipped with a transmitter 310 incommunication with the controller 306.

The sensor 308 may be of various forms to capture the desiredphysiological conditions of the patient. For example, the measurementdevice 102 may be an implantable medical device such as a pacemaker thatincludes leads and circuitry forming a sensor that measures electricalactivity of the heart such as the QRS complex, pulse rate, oratrioventricular delay. Other sensors are also applicable, such as aninternal or external blood pressure or body temperature sensor.

Although the device 202 is shown as being an external device used todetect proximity to define a patient context, other forms of devices foruse in detecting context in conjunction with a measurement device 102may be used as well. For example, a detector device such as a tiltswitch (not shown) may be included within the measurement device 102 tocapture the tilt of the patient's body and can trigger the controller306 to respond in a particular way in place of the receiver 304triggering the controller 306. For example, the tilt switch may causethe controller 306 to begin taking measurements through the sensor 308of a particular physiological condition only when the patient has becomerecumbent as determined from the output of the tilt switch. Additionallyor alternatively, the tilt switch may cause the controller 306 to choosea particular mode of therapy when the patient has become recumbent asopposed to upright.

Additionally, other situations may utilize proximity sensing todetermine the patient context. For example, in FIG. 4 the patient 100 isdriving a car by interacting with various controls 402 of the car. Theexternal device 202 is placed proximal to the seat of the driver andoutputs a signal 204 such as when the car is running by receiving powerfrom a switched power connection of the automobile. The measurementdevice 102 is coupled to the patient 100 and becomes within range of thesignals 204 once the patient 100 sits in the driver's seat. Therefore,upon beginning operation of the car, the external device 202 sends thesignal 204 that causes the measurement device 102 to respond in aparticular manner, such as by beginning measurement of a physiologicalcondition or flagging the measurements being made as occurring duringthe new patient context. Additionally or alternatively, the device 102may begin application of a particular mode of therapy suited for apatient driving a car when receiving the signal 204 of FIG. 4.

FIG. 5 provides an example of logical operations that may be performedby a measurement device 102 to detect and respond to a particularcontext to correlate the detected context with the measurement ofphysiological conditions and/or to apply a particular mode of therapy.As shown, the context is a patient context detected through proximity toa beacon transmitter 202 such as the situation shown in FIG. 2. Thecontroller 306 of the measurement device 102 continuously orperiodically polls the output of the receiver 304 to determine whetherthe beacon signal 204 has been received at query operation 502. If thebeacon has been received, then the controller 306 begins recording tomemory the physiological measurements taken from the sensor 308 atrecord operation 504 and/or begins applying a first mode of therapy attherapy operation 508. Additionally or alternatively, the controller 306may begin outputting the measurements through the transmitter 310 to theexternal device 202 or another device that receives and records data tomemory. Upon query operation 502 detecting that the beacon is not beingreceived, then the recording of the physiological measurements stops atstop operation 506. Additionally or alternatively, once query operationdetects that the beacon is not being received, a second mode of therapybegins in at therapy operation 510.

FIG. 6 shows another example of the logical operations of a measurementdevice 102 detecting a context and responding accordingly. Theseoperations also apply to the situation of FIG. 2 where the patientcontext is set forth by proximity of the patient 100. The operationsbegin at record operation 602 where the controller 306 records themeasurements received from the sensor 308. At query operation 604, thecontroller 306 detects whether the beacon signal 204 is received duringthe time the measurements are being recorded. If not, then thecontroller 306 continues to record the physiological measurements atrecord operation 602. Alternatively, the controller 306 begins flaggingthe measurements with an indicator based on the lack of beacon receptionat flag operation 608. Additionally or alternatively, the controller 306begins application of a second mode of therapy at therapy operation 612.

When query operation 604 does detect that the beacon signal 204 isreceived, then the controller 306 begins flagging the recordedmeasurements with an indicator based on the presence of beacon receptionat flag operation 606. Additionally or alternatively, the controller 306begins application of a first mode of therapy at therapy operation 610in response to the beacon being received. The first and second modes oftherapy may also rely upon the physiological measurements being made atrecord operation 602 to control therapy as necessary to address themedical condition of the patient 100, such as speeding up or slowingdown the pulse rate based on the current pulse rate being recorded aswell as the context of the recording as indicated by the presence orabsence of the beacon signal.

The measurements may be flagged at flag operations 606 or 608 to simplyindicate that a predefined patient context such as lying down isoccurring while the measurements are being recorded. Alternatively, suchas where multiple patient contexts may be detectable by providing IDsfrom the external devices 202 (i.e., bedside vs. car), the ID or otherpatient context descriptor may be logged in association with thephysiological measurements being made. Subsequently, a physician ormachine reviewing the measurements may account for the patient contextthat occurred, such as by applying a known correction factor to themeasurements for the known patient context to normalize the measurementsrelative to a baseline context.

FIG. 7 shows another illustrative system for detecting context whenmeasuring a physiological condition or applying a mode of therapy byproviding the beacon signal from the measurement device 710 rather thanthe external device 702. The system of FIG. 7 employs a measurementdevice 710 that includes a transmitter 716 coupled to a controller 712that is also coupled to a sensor 714. The controller 712 receives themeasurements from the sensor 714 and passes the measurements eithercontinuously or periodically to the transmitter 716. The transmittereither continuously or periodically outputs a signal 718 encoded withthe measurement data. Because battery life is typically of concern for amedical device coupled to a patient, intermittent transmissions from thetransmitter 716 may be appropriate for a particular situation to reducethe drain on the power source for the measurement device 710.

The signal 718 is received by a receiver 706 of an external device 702when the device 702 is within transmission range of the measurementdevice 710 while the transmitter 716 is providing the signal 718. Acontroller 704 of the device 702 acts as a data logger to store the datain memory or forward that data on to another device or network. Thecontroller 704 may be configured to respond to receiving the signal fromthe transmitter 716 by beginning the recording of the data as soon asthe receiver 706 is in range. Alternatively, the controller 704 may beconfigured to begin recording data, flagging data, or logging thepatient context only upon an indication within the signal 718 that aparticular patient context has been detected by the measurement device.For example, an incorporated tilt switch may indicate that the patientis recumbent, and this indication is provided through the signal 718 tothe controller 704 to control how and whether the measurement data ofthe signal 718 is recorded.

As another alternative, transmission from the measurement device 710 maybe controlled in other ways based upon patient context determined by adevice coupled to the patient, such as a tilt switch in communicationwith the controller 712. For example, the transmission of signal 718 mayoccur only during periods when the patient is recumbent. So, the systemof FIG. 7 may be configured so that recording of the physiologicalmeasurements occurs at the device 702 only when the devices are inproximity and the patient is recumbent. Additional contextual conditionsmay be imposed as well, such as recording the data only when theenvironmental sensor 708 has a certain output or the environmentalmeasurement may be logged with the measurement data being recorded.

Furthermore, the controller 704 may make a determination as to what modeof therapy should be provided based on whether the signal 718 is beingreceived. In this scenario, the device 702 must have access to atransmitter and a device coupled to the patient 100 must include areceiver such that the controller 704 may convey instructions to thedevice coupled to the patient 100 to initiate execution of a particularmode of therapy.

FIG. 8 shows another illustrative system to detect a patient contextthrough proximity sensing that utilizes an external device 802 thatcommunicates with a first assembly 812 coupled to the patient 100 thatincludes a transponder chip 814. For example, the first assembly 812 maybe a bracelet or other jewelry worn by the patient 100 that includes thetransponder chip 812. The transponder chip 814 is responsive to anelectromagnetic wave by reflecting the wave with an ID encoded in thereflection.

An external device 802 includes a transmitter 808 that transmits anelectromagnetic wave 824 that may be reflected by the transponder chip814 when the transponder chip 814 is within range of the external device802. A receiver 810 included in the external device 802 receives thereflected electromagnetic wave from the transponder chip 814 andprovides the ID of the reflected wave to a controller 804. Thus, therange of the transponder chip 814 for receiving and reflecting anelectromagnetic wave defines the area of proximity that is used todetect a patient context such as lying down or driving. The controller804 then causes a second transmitter 806 to transmit a signal 826 to ameasurement device 816 upon receiving the reflected wave from thetransponder chip 814.

The measurement device 816 is coupled to the patient 100, eitherexternally or as an implant. The measurement device 816 includes acontroller 818 coupled to a receiver 822 and a sensor 820. The receiver822 receives the signal 826 transmitted by the external device 802. Uponreceiving the signal 826, a controller 818 coupled to the receiver 822begins recording physiological measurements made by a sensor 820,flagging measurements already being made, or logs a patient context withthe measurements. As discussed above in relation to other illustrativesystems, the controller 818 may transmit the measurement and contextinformation to additional devices if the measurement device 816 isequipped with a transmitter. Additionally or alternatively, thecontroller 818 may activate a mode of therapy depending upon whether thesignal 826 is being received.

FIG. 9 shows the logical operations of another system for detectingcontext in relation to physiological conditions of a patient. Thelogical operations of FIG. 9 provide monitoring of ingress and egressfrom a particular location that is associated with a known patientcontext. For example, it may be utilized to detect that a patient isentering or exiting a room used for exercise where exercise is a patientcontext that results in measurements to be recorded or ignored or whereexercise dictates a particular mode of therapy to be employed. A systemsuch as that shown in FIG. 3 is appropriate where an external devicesuch as device 202 transmits one or more beacon signals at the doorway.As the patient 100 enters or exits through the doorway, the measurementdevice 102 momentarily receives the beacon signal(s). Rather thanmeasuring, or not measuring, during the period when the beacon signal(s)is in range, the measurement device 102 begins recording uponmomentarily receiving the signal at one time and stops measuring uponmomentarily receiving the signal at another time. Likewise, the device102 may initiate a first therapy mode upon receiving the signal(s) atone time and then initiate a second mode of therapy upon receiving thesignal(s) at a subsequent time.

The logical operations of the controller of the measurement device 102for this system begin at query operation 902 where the controllerdetects whether the patient has entered (or exited) the room bydetermining if the receiver has momentarily received the beacon signalfor the first time. As an alternative, multiple beacons may be providedat the doorway so that the beacons are received in one sequence uponingress and are received in the reverse order upon egress and the device102 can then determine whether the patient 100 is entering or exiting.If the beacon signals are not received, then query operation 902 repeatsuntil the reception of the beacon signal has occurred. Alternatively,the controller may begin to record the physiological measurement fromthe sensor at record operation 914 and then flag the recordedmeasurements with an indicator based on the patient's non-entry at flagoperation 916. As another alternative, the controller may initiate orcontinue the application of a second therapy mode at therapy operation918.

Once query operation 902 detects that the beacon signal has beenreceived, the controller begins recording the physiological measurementsof the sensor, logging the patient context with the measurements beingrecorded, or applying a correction factor to the measurements at recordoperation 904. Additionally or alternatively, the controller beginsflagging the measurements with an indicator based on the patient's entryat flag operation 910. Additionally or alternatively, the controllerinitiates application of a first mode of therapy at therapy operation912.

During this time, the controller again detects whether the beacon signalhas been momentarily received again at query operation 906. If not, thenthe controller continues to correlate the physiological measurementswith the context as was started at record operation 904 and/or flagoperation 906 or continues to apply the first mode of therapy. Oncequery operation 906 detects that the receiver has received the beaconsignal again or in the order of egress for a multi-beacon setup, thenthe controller stops correlating the physiological measurements with thepatient context defined by the entry (or exit) to the room at stopoperation 908. Stopping correlation of the measurements with the contextmay involve stopping the recording of measurements altogether, stoppingthe flagging of measurements being recorded, stopping or changing thepatient context being logged in association with the measurements beingrecorded, or stopping or changing the correction factors applied to themeasurements. Furthermore, after exiting, query operation 902 willdetect that the patient has not re-entered so that the second therapymode will be initiated by the controller at therapy operation 918.

The controller of the various devices discussed herein may be of variousforms of a processing device for implementing the logical operationsalso discussed above. For example, the controller may be hardwireddigital logic such as an application specific integrated circuit. Asanother example, the controller may be a general-purpose programmableprocessing device implementing code stored in memory.

While the invention has been particularly shown and described withreference to illustrative embodiments thereof, it will be understood bythose skilled in the art that various other changes in the form anddetails may be made therein without departing from the spirit and scopeof the invention.

What is claimed is:
 1. A system for monitoring physiological conditionsof an ambulatory patient capable of moving among a plurality ofenvironmental locations external to the patient based on a detection ofat least one posture associated with the patient, the system comprising:a detector, including a first device positioned in one of the pluralityof environmental locations and a second device attached to theambulatory patient, the first and second devices configured to cooperateto detect the patient being within a specified range of the first deviceand to determine the at least one posture associated with the patient inresponse to the patient being within the specified range of the firstdevice; a physiological sensor that is responsive to a physiologicalcondition of the patient; and a processing device configured toautomatically measure from the physiological sensor at least onephysiological condition of the patient in response to the detection ofthe at least one posture.
 2. The system of claim 1 further comprising atransmitter that outputs a signal encoded with the measurements made bythe processing device from the physiological sensor.
 3. The system ofclaim 1, wherein the processing device is configured to flag themeasurements taken in response to the detection of the at least oneposture.
 4. The system of claim 1, wherein the physiological sensorcomprises a pulse rate sensor.
 5. The system of claim 1, wherein theprocessing device is configured to record measurements of thephysiological condition in response to the detection of a predefinedpatient posture.
 6. The system of claim 1, wherein the processing deviceis configured to store the measurements of the physiological conditionin association with the at least one detected posture.
 7. The system ofclaim 1, wherein the processing device is configured to correct themeasurements of the at least one physiological condition by applicationof a correction factor associated with the detected at least oneposture.
 8. The system of claim 1, wherein the detector comprises atleast one transmitter external to the patient and a receiver responsiveto the transmitter.
 9. The system of claim 8, wherein the receiver isimplantable.
 10. The system of claim 1, wherein the detector comprises atransmitter external to the patient and a transponder responsive to thetransmitter.
 11. The system of claim 1, wherein the detector comprisesmultiple transmitters external to the patient and a receiver responsiveto the transmitters, wherein the transmitters transmit data regardingmultiple contexts.
 12. A system for monitoring physiological conditionsof an ambulatory patient capable of moving among a plurality ofenvironmental locations external to the patient, the system comprising:a detector including a first device positioned in one of the pluralityof environmental locations and a second device attached to theambulatory patient, the first and second devices configured to cooperateto detect the patient being within a specified range of the first deviceand to determine at least one posture associated with the patient inresponse to the patient being within the specified range of the firstdevice; a physiological sensor that is responsive to a physiologicalcondition of the patient; and a processing device that is configured, inresponse to the detection of the at least one posture, to: automaticallyperform measurements from the physiological sensor of at least onephysiological condition of the patient; flag the measurements; andrecord the measurements.
 13. The system of claim 12, wherein theprocessing device is configured to store the measurements in response tothe detection of a predefined patient posture.
 14. The system of claim12, wherein the physiological sensor comprises a pulse rate sensor. 15.The system of claim 12, wherein the processing device is configured tocorrect the measurements of the at least one physiological condition byapplication of a correction factor associated with the detected at leastone posture.
 16. A system for monitoring physiological conditions of anambulatory patient capable of moving among a plurality of environmentallocations external to the patient, the system comprising: a detector,including a first device positioned in one of the plurality ofenvironmental locations and a second device attached to the ambulatorypatient, the first and second devices configured to cooperate to detectthe patient being within a specified range of the first device and todetermine at least one posture associated with the patient in responseto the patient being within the specified range of the first device; aphysiological sensor that is responsive to a physiological condition ofthe patient; a processing device configured to automatically performmeasurements from the physiological sensor of at least one physiologicalcondition of the patient in response to the detection of the at leastone posture; a transmitter configured to output the measurements of theat least one physiological condition; and a receiver that is responsiveto the transmitter.
 17. The system of claim 16, wherein the transmitteris external to the patient.
 18. The system of claim 16, wherein thetransmitter is configured to output a signal encoded with themeasurements made by the processing device from the physiologicalsensor.
 19. The system of claim 16, wherein the transmitter isconfigured to transmit data regarding multiple contexts.
 20. The systemof claim 16, wherein the transmitter is configured to transmit dataregarding at least on of a patient context or an environmental context.